Geofísica

We present velocity anomalies for the upper mantle beneath the Pantanal, Paraná, and Chaco‐Paraná basins, using teleseismic P‐wave tomography.

Travel time tomography proved to be an attractive tool to study the upper mantle and lithosphere. In the last decades, this technic has been applied to the whole Earth generating interesting results without any expensive computation infrastructure. We are applying it to a set of temporary stations that were deployed to study the Pantanal-Chaco basin located at southeast Brazil. Our database is composed of 66 seismic stations and 820 teleseismic events (between 30 and 95 degrees).

The Great Oxidation Event (GOE) has been defined as the time interval when sufficient atmospheric oxygen accumulated to prevent the generation and preservation of mass-independent fractionation of sulfur isotopes (MIF-S ; ∆33S) in sedimentary rocks. However, the timing and significance of the loss of ∆33S signals in the sedimentary record remains unclear. Existing correlations in S. Africa suggest that the GOE was rapid and globally synchronous at ~2.32 Ga. In contrast, after 2.45 Ga to beyond 2.31 Ga, the slow disappearance of anomalous ∆33S signals in W.